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Network+ lab 13 of 27

DHCP: scopes and options with reservations and relay

Run DHCP for head office and a branch from one server. You relay requests across a router, find and fix an exhausted scope, add options such as DNS and lease time, reserve an address for a printer, and capture the four DORA messages.

Run this lab

It needs Lite: its 6 nodes are set to 6 vCPU and 4,608 MB in total. That fits the free demo too.

In your workspace: Shared, then CompTIA Network Plus N10-009 guided labs, then 13 - DHCP - scopes and options with reservations and relay

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Level
Intermediate
Time
About 60 minutes
Nodes need
6 vCPU, 4,608 MB
Smallest plan
Lite

The scenario

Harbour Logistics runs DHCP centrally on its head-office router R1, for head office and for the branch behind R2. Head office works. At the branch, nothing gets an address, and the network printer must always have 10.20.20.20, because the label printers in the warehouse are configured to print to it.

DeviceInterfaceAddressNotes
R1Gi0/010.10.10.1/24HQ LAN, PC1
R1Gi0/110.0.12.1/30to branch R2
R2Gi0/010.0.12.2/30to R1
R2Gi0/110.20.20.1/24branch LAN: PC2, PC3, PRN1
PRN1eth0reserved 10.20.20.20printer, MAC 02:00:5e:20:00:50

Address policy: in both LANs, .1 to .49 are reserved for routers, printers and servers, so DHCP must hand out .50 to .254 only. Clients get the DNS server 10.10.10.53, the domain harbour.lab, and a 12-hour lease.

What you’ll practise

  • Explain the DORA exchange and why DHCP needs a relay across routers
  • Configure DHCP scopes with exclusions, default gateway, DNS, domain and lease options
  • Configure a DHCP relay (IP helper)
  • Diagnose and fix address pool exhaustion
  • Reserve an address for a device by its client identifier
  • Capture DHCP with tcpdump and read the bindings table

The tasks

  1. Prepare the printer
  2. Watch DHCP work at head office
  3. Relay DHCP across the router
  4. Fix the exhausted scope
  5. Add the scope options
  6. Reserve the printer's address and capture DORA

The Lab Tasks pane has the scenario, these tasks, the checks to run, hints and the full solution.

Topology and devices

The network as it opens in EVE-NG, drawn from the lab’s own canvas, and the image each node runs.

Topology of DHCP - scopes and options with reservations and relay6 nodes and 1 network, 6 links. Every link is listed as text below the diagram.R1R2PC1PC2PC3PRN1Branch-LANeth0eth0eth0Gi0/1Gi0/0eth0Gi0/1Gi0/0
6 nodes and 1 network, with the interface names each link uses. On a narrow screen, scroll the diagram sideways.
Every link, as text
  • R1 Gi0/0 to PC1 eth0
  • R1 Gi0/1 to R2 Gi0/0
  • R2 Gi0/1 to Branch-LAN (network)
  • PC2 eth0 to Branch-LAN (network)
  • PC3 eth0 to Branch-LAN (network)
  • PRN1 eth0 to Branch-LAN (network)
Nodes in DHCP: scopes and options with reservations and relay, with the image each runs and the vCPU and RAM it’s set to
NodeDeviceImage in Add NodeSet to
R1Cisco IOSvvios-adventerprisek9-m.SPA.159-3.M61 vCPU, 512 MB
R2Cisco IOSvvios-adventerprisek9-m.SPA.159-3.M61 vCPU, 512 MB
PC1VPCS hostBuilt in to EVE-NGCounted as 1 vCPU, 1,024 MB
PC2VPCS hostBuilt in to EVE-NGCounted as 1 vCPU, 1,024 MB
PC3VPCS hostBuilt in to EVE-NGCounted as 1 vCPU, 1,024 MB
PRN1Alpine Linuxclbalpinebase-alpine-base-3-20-31 vCPU, 512 MB

How to open this lab

  1. Sign in to your workspace at lab.cloudlabbox.com.

  2. In File Manager, open Shared, then the folder CompTIA Network Plus N10-009 guided labs.

  3. Open 13 - DHCP - scopes and options with reservations and relay and start its nodes, then open Lab Tasks for the scenario and the steps.

The lab is read-only. You can start the nodes and configure the devices, but changes to the topology can’t be saved. To change it, rebuild it in your own folder.

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CloudLabBox is independent of CompTIA, Cisco and Netgate. The lab follows exam topics and isn’t vendor training material; vendor names identify the exams and the images in the workspace.